Heat pump trouble

mkp

Member
May 7, 2017
9
Farnham, UK
Hi - I am using an air sourced heatpump to heat my Intex above ground pool. Last year the pool heater worked well but this year I can't get enough water flow to start the heater. I have bought a new circulation pump (a 3/4 HP one - much bigger than is needed). I can hear some air in the system near to the heater but can't get rid of it. Any suggestions would be really appreciated, many thanks.
 

mkp

Member
May 7, 2017
9
Farnham, UK
Welcome to TFP!

Sounds like the filter is clogged?
I have cleaned the filter and checked the flow rate, the pump is delivering almost 6 cubic m/hr and the heat pump needs 4.6 to run. There is some gurgling from time to time so it may be an air problem but I have no idea how to get the air out of the heat pump link as the pipe work is sealed
 

pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
25,173
FL panhandle
So, it is giving a low flow error? If the heater is connected with unions you can loosen the upper union to let out any air. But, a 3/4hp pump should be able to easily push any air out of the plumbing. Add your pool info to your sig so that we know what we are helping with, more here about adding a sig, Pool School - Read This BEFORE You Post. And maybe post a pic of the equipment to see if we can see anything.
 

mkp

Member
May 7, 2017
9
Farnham, UK
DSC06372.jpgMany thanks for your help. It is a flow problem, if I wiggle the upper pipe enough the heat pump will operate for a few seconds. It may be that the flow paddle is not as sensitive as it should be?
 

pooldv

Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
Aug 10, 2012
25,173
FL panhandle
Most heat pumps have a pressure switch that reads water pressure, not water flow. What does the pressure gauge read on the filter? What is clean pressure vs current pressure? How does the water flow feel from the return? Normal? Good flow?
 

Mickelin

LifeTime Supporter
Jun 3, 2015
261
Stockholm, Sweden
1. Set the sandfilter valve in bypass mode and close the heatpump bypass valve. That provides full flow through the heatpump. Feel the flow from the return, should now be strong.
2. If flow is weak, then he problem is airleak or the circulation pump.
3. If flow is strong but heatpump still wont start, then the problem is the flow sensor or the heatpump controller.
4. If the heatpump starts, put the sandfilter valve back in filter mode. (always shut off the circulation pump while changing position of the valve).
5. If heatpump now wont start, the problem is a clogged sandfilter, try deep cleaning it if backwash is not enough.
 

mkp

Member
May 7, 2017
9
Farnham, UK
Most heat pumps have a pressure switch that reads water pressure, not water flow. What does the pressure gauge read on the filter? What is clean pressure vs current pressure? How does the water flow feel from the return? Normal? Good flow?


THe sand filter is running at 1 bar (mid amber range). The heat pump has a strange dial on it. This usually hovers at the lower end (with or without circulation pump running as shown in the picture) but the dial usually rises a lot as the heat pump starts and then drops back after a few seconds. The water flow feels strong from the return. I am not sure what clean pressure is?

DSC06378.jpg
 

mkp

Member
May 7, 2017
9
Farnham, UK
1. Set the sandfilter valve in bypass mode and close the heatpump bypass valve. That provides full flow through the heatpump. Feel the flow from the return, should now be strong.
2. If flow is weak, then he problem is airleak or the circulation pump.
3. If flow is strong but heatpump still wont start, then the problem is the flow sensor or the heatpump controller.
4. If the heatpump starts, put the sandfilter valve back in filter mode. (always shut off the circulation pump while changing position of the valve).
5. If heatpump now wont start, the problem is a clogged sandfilter, try deep cleaning it if backwash is not enough.
Many thanks - it seems to be number 3 - the sensor or controller.
 

CJadamec

TFP Expert
Apr 29, 2016
2,267
Quaker Hill, CT
The gauge you too a picture of is the refrigerant gauge on the compressor of the heat pump. It's showing the compressor outlet pressure which according to the spec sheet in the picture should be a max of 4.2MPa (~600psi). With the compressor off the gauge is reading the high side pressure of 1.3MPa which if you read the red scale in the middle matches what I'm guessing your outside air temp of about 18* C. In other words that gauge is telling you the refrigerant system doesn't have a leak. It should rise to close to 4.2MPa when the unit starts then back off to I'm guessing around ~3MPa after the TX valve opens.

Long story short that gauge is doing exactly what it should be doing.
 

mkp

Member
May 7, 2017
9
Farnham, UK
The gauge you too a picture of is the refrigerant gauge on the compressor of the heat pump. It's showing the compressor outlet pressure which according to the spec sheet in the picture should be a max of 4.2MPa (~600psi). With the compressor off the gauge is reading the high side pressure of 1.3MPa which if you read the red scale in the middle matches what I'm guessing your outside air temp of about 18* C. In other words that gauge is telling you the refrigerant system doesn't have a leak. It should rise to close to 4.2MPa when the unit starts then back off to I'm guessing around ~3MPa after the TX valve opens.

Long story short that gauge is doing exactly what it should be doing.
Many thanks, this makes a lot of sense - why don't they put this sort of explanation into the instructions? The instruction pack is so poor, it has been auto-translated from some other language into English.
 

CJadamec

TFP Expert
Apr 29, 2016
2,267
Quaker Hill, CT
I'm amazed there is a gauge like that on a residential heat pump in the first place. You would never see that on US models. It's a shame because they are super useful when troubleshooting the compressor system.
 

Mickelin

LifeTime Supporter
Jun 3, 2015
261
Stockholm, Sweden
Yeah, the manual really sucks. I have the Swedish version, just as poor. Does the display show the EE3 error code, indicating low flow? Or any other code? If you are sure that the flow is good and you are confident messing with electrical devices, you could try disconnecting the flow switch. The schematic is decent and the connection is easy to find. Just unscrew the right wire from the panel. If it still doesn't start, you need to get a technician to have a look at it, probably replace the circuit board.
 

mkp

Member
May 7, 2017
9
Farnham, UK
Yeah, the manual really sucks. I have the Swedish version, just as poor. Does the display show the EE3 error code, indicating low flow? Or any other code? If you are sure that the flow is good and you are confident messing with electrical devices, you could try disconnecting the flow switch. The schematic is decent and the connection is easy to find. Just unscrew the right wire from the panel. If it still doesn't start, you need to get a technician to have a look at it, probably replace the circuit board.
Many thanks to you all. I tried shorting out the switch and the unit started, so I drained the system, pulled the flow switch out and found that you can adjust the position of the sensor on the top of the switch. This makes the switch more/less sensitive. Once I did this the system works perfectly - the heat pump starts up when there is flow and stops when there is no flow. So much for the manual saying that you need to call a service person ....
 
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